Fixing device and image forming apparatus including a friction reducer including a lubricant

Abstract

A fixing device includes a fixing rotator that is endless and rotatable in a rotation direction and a heater to heat the fixing rotator. A pressure rotator contacts an outer circumferential surface of the fixing rotator. A nip formation pad presses against the pressure rotator via the fixing rotator to form a fixing nip between the fixing rotator and the pressure rotator. The nip formation pad includes an upstream portion disposed upstream from the fixing nip in the rotation direction of the fixing rotator. A recess is disposed in the upstream portion of the nip formation pad. A friction reducer is sandwiched between the nip formation pad and the fixing rotator and bears a lubricant.

What is claimed is: 
     
       1. A fixing device comprising:
 a fixing rotator that is endless and rotatable in a rotation direction; 
 a heater to heat the fixing rotator; 
 a pressure rotator to contact an outer circumferential surface of the fixing rotator; 
 a nip formation pad to press against the pressure rotator via the fixing rotator to form a fixing nip between the fixing rotator and the pressure rotator, 
 the nip formation pad including an upstream portion disposed upstream from the fixing nip in the rotation direction of the fixing rotator; 
 a plurality of recesses disposed in the upstream portion of the nip formation pad, the plurality of recesses being disposed on one line which is parallel to an axial direction of the fixing rotator; and 
 a friction reducer being sandwiched between the nip formation pad and the fixing rotator and bearing a lubricant. 
 
     
     
       2. The fixing device according to  claim 1 ,
 wherein the friction reducer is applied with the lubricant. 
 
     
     
       3. The fixing device according to  claim 1 ,
 wherein the friction reducer is impregnated with the lubricant. 
 
     
     
       4. The fixing device according to  claim 1 ,
 wherein the nip formation pad further includes an upstream end in the rotation direction of the fixing rotator. 
 
     
     
       5. The fixing device according to  claim 4 ,
 wherein the plurality of recesses adjoin the upstream end of the nip formation pad. 
 
     
     
       6. The fixing device according to  claim 4 ,
 wherein the plurality of recesses are disposed in proximity to the upstream end of the nip formation pad. 
 
     
     
       7. The fixing device according to  claim 1 ,
 wherein the nip formation pad further includes a nip forming portion disposed opposite the fixing nip, and 
 wherein the upstream portion is disposed upstream from the nip forming portion in the rotation direction of the fixing rotator. 
 
     
     
       8. The fixing device according to  claim 1 ,
 wherein the upstream portion of the nip formation pad includes a nip-side face that is other than the plurality of recesses, the nip-side face to press against the fixing rotator via the friction reducer. 
 
     
     
       9. The fixing device according to  claim 1 ,
 wherein the plurality of recesses project beyond the friction reducer in a direction opposite the rotation direction of the fixing rotator. 
 
     
     
       10. The fixing device according to  claim 1 ,
 wherein the nip formation pad is made of one of resin, metal, and copper. 
 
     
     
       11. The fixing device according to  claim 1 ,
 wherein each of the plurality of recesses includes a corresponding groove. 
 
     
     
       12. The fixing device according to  claim 1 ,
 wherein the friction reducer includes a sheet and the fixing rotator includes an endless belt. 
 
     
     
       13. The fixing device according to  claim 1 , wherein:
 the plurality of recesses are on a surface of the nip formation pad that is perpendicular to a surface of the nip formation pad that presses against the pressure rotator via the fixing rotator. 
 
     
     
       14. The fixing device according to  claim 1 , wherein:
 the plurality of recesses are in a surface of the nip formation pad that presses against the pressure rotator via the fixing rotator. 
 
     
     
       15. A fixing device comprising:
 a fixing rotator that is endless and rotatable in a rotation direction; 
 a heater to heat the fixing rotator; 
 a pressure rotator to contact an outer circumferential surface of the fixing rotator; 
 a nip formation pad to press against the pressure rotator via the fixing rotator to form a fixing nip between the fixing rotator and the pressure rotator, 
 the nip formation pad including:
 a nip forming portion disposed opposite the fixing nip; and 
 an upstream portion disposed upstream from the nip forming portion in the rotation direction of the fixing rotator,
 the upstream portion including a recess disposed substantially at a center of the nip formation pad in a longitudinal direction of the nip formation pad, the recess being recessed toward the nip forming portion in the rotation direction of the fixing rotator; and 
 
 
 a friction reducer being sandwiched between the nip formation pad and the fixing rotator and bearing a lubricant, 
 wherein the upstream portion further includes one of a linear slope defined by the recess and a curve defined by the recesses, the one of a linear slope defined by the recess and a curve defined by the recesses increasing a length of the nip formation pad in the rotation direction of the fixing rotator from the center to a lateral edge of the nip formation pad in the longitudinal direction of the nip formation pad. 
 
     
     
       16. The fixing device according to  claim 15 ,
 wherein the one of a linear slope defined by the recess and a curve defined by the recesses includes the linear slope defined by the recess. 
 
     
     
       17. The fixing device according to  claim 15 ,
 wherein the one of a linear slope defined by the recess and a curve defined by the recesses includes the curve defined by the recess. 
 
     
     
       18. A fixing device comprising:
 a fixing rotator that is endless and rotatable in a rotation direction; 
 a heater to heat the fixing rotator; 
 a pressure rotator to contact an outer circumferential surface of the fixing rotator; 
 a nip formation pad to press against the pressure rotator via the fixing rotator to form a fixing nip between the fixing rotator and the pressure rotator, 
 the nip formation pad including an upstream portion disposed upstream from the fixing nip in the rotation direction of the fixing rotator; 
 a recess disposed in the upstream portion of the nip formation pad; and 
 a friction reducer being sandwiched between the nip formation pad and the fixing rotator and bearing a lubricant, 
 wherein the recess projects beyond the friction reducer in a direction opposite the rotation direction of the fixing rotator.